Q1. [2] § 1.1 CHEMICAL EQUATIONS § 1.1.1 Writing a Chemical Equation § 1.1.2 Balanced Chemical Equations
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
MnO₂ + 4HCl ⟶ MnCl₂ + 2H₂O + Cl₂
Previously asked in CBSE board exam
2023 31/6/1 Q21
Generated by claude-sonnet-4-6 · 2026-06-14 10:27 · grounding rag
Model Answer
Yes, — it is a redox reaction.
In this reaction, Mn in MnO₂ goes from +4 to +2 oxidation state (gains electrons → reduction), while Cl in HCl goes from −1 to 0 in Cl₂ (loses electrons → oxidation). Since both oxidation and reduction occur simultaneously, it is a redox reaction.
Explanation
- A redox reaction must show both oxidation and reduction occurring simultaneously — mention both clearly for full marks.
- Assign oxidation states to Mn (+4 → +2) and Cl (−1 → 0) to justify your answer; this is what examiners look for.
- The textbook defines oxidation as gain of oxygen/loss of hydrogen (or electrons) and reduction as the reverse — either definition is acceptable here; oxidation state method is more precise.
- 1 mark for correct identification + 1 mark for valid justification with oxidation states.
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